Researchers Detect a Loophole in Chronic Lymphocytic Leukemia Treatment

A team of researchers in Italy and Austria has determined that a drug approved to treat chronic lymphocytic leukemia (CLL) may be less effective in a particular subset of patients. The study, which will be published January 4 in the Journal of Experimental Medicine, reveals that ibrutinib has a diminished capacity to delocalize and kill tumor cells expressing an adhesive protein called CD49d, but combining ibrutinib treatment with drugs that block CD49d activation could prevent the tumor cells from sheltering in lymphoid organs.

CLL is the most common leukemia in adults, and it is characterized by the presence of cancerous B cells that accumulate in the lymph nodes, spleen, and liver. Ibrutinib reallocates CLL cells from lymph nodes into the blood by inhibiting Bruton’s tyrosine kinase (BTK), a key enzyme in the B cell receptor (BCR) signaling pathway.

BCR signaling promotes the survival and differentiation of normal, healthy B cells in several ways, including by activating the adhesion receptor VLA-4, which attaches B cells to other, supportive cells within lymph nodes. One of the subunits of VLA-4, CD49d, is highly expressed in about 40% of CLL patients. These patients tend to have poorer outcomes than patients that do not express CD49d, but the role of VLA-4 in CLL is unclear.

A team of researchers led by Antonella Zucchetto and Valter Gattei of the CRO Aviano National Cancer Institute in Italy and Tanja Nicole Hartmann of the Paracelsus Medical University in Salzburg, Austria, found that BCR signaling can activate VLA-4 in CD49d-expressing CLL cells, thereby enhancing the cells’ adhesiveness. Even though ibrutinib treatment impaired BCR signaling in these cells, it was unable to fully hinder the pathway from activating VLA-4 and enhancing cell adhesion.

The researchers analyzed three different cohorts of CLL patients from Italy and the United States. In all three groups, patients expressing higher levels of CD49d showed reduced responses to ibrutinib treatment: the drug appeared to be less able to displace tumor cells from lymph nodes into the blood, resulting in decreased lymph node shrinkage and shorter progression-free survival times.

“Our results suggest that VLA-4–expressing CLL cells residing in the secondary lymphoid organs can receive BCR-mediated stimuli that can activate VLA-4 even in the presence of ibrutinib,” says Zucchetto. “This activation leads to enhanced retention of VLA-4–positive CLL cells in tissue sites, thereby affecting patient outcome.”

In addition to the ibrutinib target BTK, BCR signaling can proceed through an alternative enzyme called phosphatidylinositide 3-kinase. The researchers found that simultaneously inhibiting both BTK and phosphatidylinositide 3-kinase completely blocked VLA-4 activation in CLL cells.

“Our data suggest that evaluation of CD49d expression in patients initiating ibrutinib therapy may identify those cases that would benefit from combination therapy approaches designed to completely block VLA-4 activation and VLA-4–mediated retention of leukemic cells in protective tissue compartments,” says Gattei.

CRI Scientists Discover Vitamin C Regulates Stem Cell Function and Suppresses Leukemia Development

Not much is known about stem cell metabolism, but a new study from the Children’s Medical Center Research Institute at UT Southwestern (CRI) has found that stem cells take up unusually high levels of vitamin C, which then regulates their function and suppresses the development of leukemia.

“We have known for a while that people with lower levels of ascorbate (vitamin C) are at increased cancer risk, but we haven’t fully understood why. Our research provides part of the explanation, at least for the blood-forming system,” said Dr. Sean Morrison, the Director of CRI.

The metabolism of stem cells has historically been difficult to study because a large number of cells are required for metabolic analysis, while stem cells in each tissue of the body are rare. Techniques developed during the study, which was published in Nature, have allowed researchers to routinely measure metabolite levels in rare cell populations such as stem cells.

The techniques led researchers to discover that every type of blood-forming cell in the bone marrow had distinct metabolic signatures – taking up and using nutrients in their own individual way. One of the main metabolic features of stem cells is that they soak up unusually high levels of ascorbate. To determine if ascorbate is important for stem cell function, researchers used mice that lacked gulonolactone oxidase (Gulo) – a key enzyme that most mammals, including mice but not humans, use to synthesize their own ascorbate.

Loss of the enzyme requires Gulo-deficient mice to obtain ascorbate exclusively through their diet like humans do. This gave CRI scientists strict control over ascorbate intake by the mice and allowed them to mimic ascorbate levels seen in approximately 5 percent of healthy humans. At these levels, researchers expected depletion of ascorbate might lead to loss of stem cell function but were surprised to find the opposite was true – stem cells actually gained function. However, this gain came at the cost of increased instances of leukemia.

“Stem cells use ascorbate to regulate the abundance of certain chemical modifications on DNA, which are part of the epigenome,” said Dr. Michalis Agathocleous, lead author of the study, an Assistant Instructor at CRI, and a Royal Commission for the Exhibition of 1851 Research Fellow. “The epigenome is a set of mechanisms inside a cell that regulates which genes turn on and turn off.  So when stem cells don’t receive enough vitamin C, the epigenome can become damaged in a way that increases stem cell function but also increases the risk of leukemia.”

This increased risk is partly tied to how ascorbate affects an enzyme known as Tet2, the study showed. Mutations that inactivate Tet2 are an early step in the formation of leukemia. CRI scientists showed that ascorbate depletion can limit Tet2 function in tissues in a way that increases the risk of leukemia.

These findings have implications for older patients with a common precancerous condition known as clonal hematopoiesis. This condition puts patients at a higher risk of developing leukemia and other diseases, but it is not well understood why certain patients with the condition develop leukemia and others do not. The findings in this study might offer an explanation.

“One of the most common mutations in patients with clonal hematopoiesis is a loss of one copy of Tet2. Our results suggest patients with clonal hematopoiesis and a Tet2 mutation should be particularly careful to get 100 percent of their daily vitamin C requirement,” Dr. Morrison said. “Because these patients only have one good copy of Tet2 left, they need to maximize the residual Tet2 tumor-suppressor activity to protect themselves from cancer.”

Researchers in the Hamon Laboratory for Stem Cell and Cancer Biology, in which Dr. Morrison is also appointed, intend to use the techniques developed as part of this study to find other metabolic pathways that control stem cell function and cancer development. They also plan to further explore the role of vitamin C in stem cell function and tissue regeneration.

Dr. Morrison is a Professor of Pediatrics at UT Southwestern, a Cancer Prevention and Research Institute of Texas (CPRIT) Scholar in Cancer Research, and a Howard Hughes Medical Institute (HHMI) Investigator. He also holds the Mary McDermott Cook Chair in Pediatric Genetics at UT Southwestern and the Kathryne and Gene Bishop Distinguished Chair in Pediatric Research at Children’s Research Institute at UT Southwestern.

CRI and UTSW co-authors include Dr. Zhiyu Zhao, Assistant Professor at CRI and of Pediatrics at UT Southwestern; Dr. Weina Chen, Associate Professor of Pathology at UT Southwestern; Dr. Corbin Meacham, Dr. Rebecca Burgess, and Dr. Malea Murphy, postdoctoral researchers; and Dr. Ralph DeBerardinis, Associate Professor at CRI, of Pediatrics, and in the Eugene McDermott Center for Human Growth & Development. Dr. DeBerardinis, who holds the Joel B. Steinberg, M.D. Chair in Pediatrics and is a Sowell Family Scholar in Medical Research at UTSW, also is the Director of CRI’s Genetic and Metabolic Disease Program and Chief of the Division of Pediatric Genetics and Metabolism at UTSW.

The National Institutes of Health, HHMI, CPRIT, and donors to the Children’s Medical Center Foundation supported this work.

Nanoparticles Reprogram Immune Cells to Fight Cancer

Researchers at Fred Hutchinson Cancer Research Center have developed biodegradable nanoparticles that can be used to genetically program immune cells to recognize and destroy cancer cells — while the immune cells are still inside the body.

In a proof-of-principle study to be published April 17 in Nature Nanotechnology, the team showed that nanoparticle-programmed immune cells, known as T cells, can rapidly clear or slow the progression of leukemia in a mouse model.

“Our technology is the first that we know of to quickly program tumor-recognizing capabilities into T cells without extracting them for laboratory manipulation,” said Fred Hutch’s Dr. Matthias Stephan, the study’s senior author. “The reprogrammed cells begin to work within 24 to 48 hours and continue to produce these receptors for weeks. This suggests that our technology has the potential to allow the immune system to quickly mount a strong enough response to destroy cancerous cells before the disease becomes fatal.”

Cellular immunotherapies have shown promise in clinical trials, but challenges remain to making them more widely available and to being able to deploy them quickly. At present, it typically takes a couple of weeks to prepare these treatments: the T cells must be removed from the patient and  genetically engineered and grown in special cell processing facilities before they are infused back into the patient. These new nanoparticles could eliminate the need for such expensive and time consuming steps.

Although his T-cell programming method is still several steps away from the clinic, Stephan imagines a future in which nanoparticles transform cell-based immunotherapies — whether for cancer or infectious disease — into an easily administered, off-the-shelf treatment that’s available anywhere.

“I’ve never had cancer, but if I did get a cancer diagnosis I would want to start treatment right away,” Stephan said. “I want to make cellular immunotherapy a treatment option the day of diagnosis and have it able to be done in an outpatient setting near where people live.”

The body as a genetic engineering lab

Stephan created his T-cell homing nanoparticles as a way to bring the power of cellular cancer immunotherapy to more people.

In his method, the laborious, time-consuming T-cell programming steps all take place within the body, creating a potential army of “serial killers” within days.

As reported in the new study, Stephan and his team developed biodegradable nanoparticles that turned T cells into CAR T cells, a particular type of cellular immunotherapy that has delivered promising results against leukemia in clinical trials.

The researchers designed the nanoparticles to carry genes that encode for chimeric antigen receptors, or CARs, that target and eliminate cancer. They also tagged the nanoparticles with molecules that make them stick like burrs to T cells, which engulf the nanoparticles. The cell’s internal traffic system then directs the nanoparticle to the nucleus, and it dissolves.

The study provides proof-of-principle that the nanoparticles can educate the immune system to target cancer cells. Stephan and his team designed the new CAR genes to integrate into chromosomes housed in the nucleus, making it possible for T cells to begin decoding the new genes and producing CARs within just one or two days.

Once the team determined that their CAR-carrying nanoparticles reprogrammed a noticeable percent of T cells, they tested their efficacy. Using a preclinical mouse model of leukemia, Stephan and his colleagues compared their nanoparticle-programming strategy against chemotherapy followed by an infusion of T cells programmed in the lab to express CARs, which mimics current CAR-T-cell therapy.

The nanoparticle-programmed CAR-T cells held their own against the infused CAR-T cells. Treatment with nanoparticles or infused CAR-T cells improved survival 58 days on average, up from a median survival of about two weeks.

The study was funded by Fred Hutch’s Immunotherapy Initiative, the Leukemia & Lymphoma Society, the Phi Beta Psi Sorority, the National Science Foundation and the National Cancer Institute.

Next steps and other applications

Stephan’s nanoparticles still have to clear several hurdles before they get close to human trials. He’s pursuing new strategies to make the gene-delivery-and-expression system safe in people and working with companies that have the capacity to produce clinical-grade nanoparticles. Additionally, Stephan has turned his sights to treating solid tumors and is collaborating to this end with several research groups at Fred Hutch.

And, he said, immunotherapy may be just the beginning. In theory, nanoparticles could be modified to serve the needs of patients whose immune systems need a boost, but who cannot wait for several months for a conventional vaccine to kick in.

“We hope that this can be used for infectious diseases like hepatitis or HIV,” Stephan said.  This method may be a way to “provide patients with receptors they don’t have in their own body,” he explained.  “You just need a tiny number of programmed T cells to protect against a virus.”

Scientists Find Possible Achilles Heel of Treatment Resistant Cancers

Scientists identify two signaling proteins in cancer cells that make them resistant to chemotherapy, and show that blocking the proteins along with chemotherapy eliminate human leukemia in mouse models.

Reporting results March 20 in Nature Medicine, researchers at Cincinnati Children’s Hospital Medical Center suggest that blocking the signaling proteins c-Fos and Dusp1 as part of combination therapy might cure several types of kinase-driven, treatment-resistant leukemia and solid tumor cancers.

These include acute myeloid leukemia (AML) fueled by the gene FLT3, lung cancers fueled by genes EGFR and PDGFR, HER2-driven breast cancers, and BCR-ABL-fueled chronic myeloid leukemia (CML), according to Mohammad Azam, PhD, lead investigator and a member of the Division of Experimental Hematology and Cancer Biology.

“We think that within the next five years our data will change the way people think about cancer development and targeted therapy,” Azam says. “This study identifies a potential Achilles heel of kinase-driven cancers and what we propose is intended to be curative, not just treatment.”

The weak spot is a common point of passage in cells (a signaling node) that appears to be required to generate cancer cells in both leukemia and solid tumors. The node is formed by the signaling proteins c-Fos and Dusp1, according to study authors. The researchers identified c-Fos and Dusp1 by conducting global gene expression analysis of mouse leukemia cells and human chronic myeloid leukemia (CML) cells donated by patients.

CML is a blood cancer driven by an enzyme called tyrosine kinase, which is formed by the fusion gene BCR-ABL. This fusion gene is the product of translocated chromosomes involving genes BCR (chromosome 22) and ABL (chromosome 9). Analysis of human CML cells revealed extremely high levels of c-FOS and DUSP1 in BCR-ABL-positive chemotherapy resistant cells.

Cancer sleeper cells

Cancer cells often become addicted to the mutated gene that causes them, such as BCR-ABL in kinase-driven chronic myeloid leukemia. Most chemotherapies work by blocking molecular pathways affected by the gene to shut down the disease process. In the case of CML, a chemotherapy called imatinib is used to block tyrosine kinase, which initially stops the disease. Unfortunately the therapeutic benefit is temporary and the leukemia comes back.

Azam and colleagues show in their CML models that signaling from tyrosine kinase – and growth factor proteins that support cell expansion (like interleukins IL3, IL6, etc.) – converge to dramatically elevate c-Fos and Dusp1 levels in the cancer cells.

Working together these molecules maintain the survival of cancer stem cells and minimal residual disease. The dormant cells wait around under the radar screen to rekindle the disease by acquiring additional genetic mutations after initially effective chemotherapy.

Azam says Dusp1 and c-Fos support the survival of cancer stem cells by increasing the toxic threshold needed to kill them. This means conventional imatinib chemotherapy will not eliminate the residual disease stem cells. Doctors can’t just increase the dose of chemotherapy because it doesn’t target the Dusp1 and c-Fos proteins that regulate toxic threshold.

Targeting c-Fos and Dusp1

After identifying c-Fos and Dusp1, the authors tested different treatment combinations on mouse models of CML, human CML cells, and mice transplanted with human leukemia cells. They also tested treatments on B-cell acute lymphoblastic leukemia (B-ALL).

The treatment combinations included: 1) solo therapy with just the tyrosine kinase inhibitor, imatinib; 2) solo treatment with just inhibitors of c-Fos and Dusp1; 3) treatment with all three combined – imatinib along with molecular inhibitors of c-Fos and Dusp1.

As suspected, treatment with imatinib alone initially stopped CML progression but the leukemia relapsed with the continued presence of residual disease cells. Treatment with c-Fos and Dusp1 inhibitors alone significantly slowed CML progression and prolonged survival in a majority of mice but wasn’t curative. Treatment for one month with c-Fos/Dusp1 inhibitors and imatinib cured 90 percent of mice with CML, with no signs of residual disease cells.

Azam and his colleagues also point to an interesting finding involving solo treatment with just the deletion of c-Fos and Dusp1. This eliminated expression of the signaling proteins and was sufficient to block B-ALL development, eradicating the disease in mouse models.

Next steps

The authors stress that because the study was conducted in laboratory mouse models, additional research is needed before the therapeutic strategy can be tested in clinical trials.
They are following up the current study by testing c-Fos and Dusp1as treatment targets for different kinase-fueled cancers, including certain types of lung cancer, breast cancers and acute forms of leukemia.

Monoclonal Antibody Drug Superior to Chemotherapy for Advanced Acute Lymphoblastic Leukemia

More than 100 centers participate in Phase III randomized trial revealing longer overall survival

A Phase III clinical trial involving 101 centers in 21 countries revealed the monoclonal antibody blinatumomab to be more effective than standard chemotherapy for treatment of advanced acute lymphoblastic leukemia (ALL). Study findings were published in the March 1 online issue of the New England Journal of Medicine.

The study, led by The University of Texas MD Anderson Cancer Center, randomly assigned 405 patients 18 years or older to groups receiving either blinatumomab or chemotherapy. Overall survival was significantly longer in the blinatumomab group with median survival of 7.7 months versus four months for those on chemotherapy. Remission rates within 12 weeks after treatment began were higher in the blinatumomab group with complete remission rates of 34 percent reported in this group versus 16 percent for those on chemotherapy. The study also showed that patients treated with blinatumomab had a lower rate of adverse effects.

While the prognosis for newly diagnosed ALL has improved over the last three decades with intensive chemotherapy regimens resulting in complete remission rates of 85 to 90 percent and long-term survival rates of 30 to 50 percent, most adult patients with the B-cell precursor ALL, the most common form, ultimately relapse and die from disease complications. The accepted standard of care is to help the patient maintain remission long enough to receive allogeneic or donor stem-cell transplantation, considered the most effective therapy.

“Among adults with relapsed ALL, remission rates are18 to 44 percent with standard chemotherapy but the duration of remission is typically short. A major goal for these patients is to induce remission with sufficient duration to prepare for stem-cell transplantation,” said Hagop Kantarjian, M.D., chair of the Department of Leukemia, and lead author for the New England Journal of Medicine paper. “In this study, 24 percent of patients in each treatment group underwent allogeneic stem cell transplantation.”

Blinatumomab, developed by Amgen, works by binding simultaneously to specific cytotoxic T-cells and B-cells, which allows the patient’s healthy T-cells to recognize and eliminate cancer stem cells called blasts.

“The activity of an immune-based therapy such as blinatumomab, which depends on functioning T-cells for its activity, provides encouragement that responses may be further enhanced and made durable with additional immune activation strategies,” said Kantarjian.

The study, designed and funded by Amgen, did not include patients who had other active cancers, relevant central nervous system conditions, autoimmune disease, acute or chronic graft-versus-host disease, chemotherapy or radiotherapy within two weeks before the study, donor stem cell transplantation within 12 weeks before the trial or autologous stem cell transplantation within six week preceding the study. Patients who received immunotherapy in the month before the trial or who were undertaking other investigational treatments were also excluded.

Mayo Clinic Researchers Find Association Between Therapy for Autoimmune Disease and Bone Marrow Disorders

Mayo Clinic researchers have found that azathioprine, a drug commonly used to treat autoimmune disease, may increase the risk of myeloid neoplasms. Myeloid neoplasms include a spectrum of potentially life-threatening bone marrow disorders, such as myelodysplastic syndromes and acute myeloid leukemia. The results are published in JAMA Oncology.

Researchers analyzed more than 40,000 patient cases with 27 common autoimmune diseases, such as Lupus, rheumatoid arthritis, among others, that were seen over a decade at Mayo Clinic. They identified 86 patients with therapy-related myeloid neoplasm. Detailed data on each patient’s drug exposures, duration and disease characteristics were collected and compared to autoimmune patients without bone marrow disorders of myelodysplastic syndromes or acute myeloid leukemia. The results concluded that only azathioprine was statistically significantly associated with an increased risk of therapy-related myeloid neoplasm. However, other agents used showed a similar trend that was not statistically significant.

“Similar associations were already documented in case reports and case series, but have never been evaluated in a broad spectrum of autoimmune diseases in that many patients and in context of individual medications,” says Raoul Tibes, M.D., Ph.D., senior author of the study and former director of the Acute and Chronic Leukemia Program at Mayo Clinic’s Arizona campus. “Interestingly, there was no association with length of time on therapy and resulting myeloid neoplasm.”

“This study, along with our current knowledge of therapy-related myeloid neoplasm, suggests that individualized drug selection and monitoring during treatment could be possible,” says Natalie Ertz-Archambault, M.D., co-author of the study. “Future genomic profiling studies may help to identify patients at risk for myeloid neoplasms when exposed to azathioprine or other drugs,” adds Dr. Tibes.

The researchers emphasize that, while the results of the study are intriguing, they should not change or replace the clinical judgments, monitoring and current standard treatments at this stage for patients with an autoimmune disease.

Despite its large size, the researchers note this study’s limitations. It was a retrospective study. Many different autoimmune diseases were analyzed, which can each affect the results. Only myelodysplastic syndromes and acute myeloid leukemia were assessed. And no definitive causal association was made between taking a particular drug and myelodysplastic syndromes or acute myeloid leukemia. Further, the number of patients with autoimmune disease developing myelodysplastic syndromes or acute myeloid leukemia is still low overall, and no prediction for individual patients can be concluded from the study.

The researchers plan to perform molecular investigations into the genetic susceptibility for therapy-related myeloid neoplasm as the next phase of the study.

New Trial Hopes to Increase Survival for Kids With Cancer, Reduce Risk of Long Term Cardiac Damage

Imagine conquering childhood cancer, only to find out that years down the road your heart may fail. Unfortunately, many children who have battled cancer face this reality. While often lifesaving, the effects of chemotherapy treatment (drugs that kill cancer cells) can take a toll on the developing body of a child, potentially resulting in life-threatening late side effects like cardiac damage.

“You go through terrible chemotherapy, achieve remission, have a new lease on life and then your heart fails,” said Dr. Todd Cooper, director of the Pediatric Leukemia/Lymphoma Program and Evans Family Endowed Chair in Pediatric Cancer at Seattle Children’s. “It’s not fair, and we’re determined to change this reality.”

Cooper is leading a new nationwide clinical trial, conducted within the Children’s Oncology Group (COG), for children and adolescents with relapsed acute myelogenous leukemia (AML) to test a drug, CPX-351, which has been designed to kill leukemia cells while minimizing damage to the heart. According to Cooper, up to 30% of patients who undergo chemotherapy for AML will have late term side effects that affect the heart. For Cooper, that’s 30% too many.

AML is an aggressive type of cancer that affects the bone marrow and blood. AML can be difficult to treat and requires intensive chemotherapy and often bone marrow transplantation.

Cooper says previous trials testing the effectiveness and efficacy of CPX-351 have shown tremendous promise in adults, and so he’s hoping to bring that same success to pediatric patients.

Bringing hope to children with acute myelogenous leukemia
Because AML is difficult to treat, standard treatment commonly involves multiple chemotherapy medicines that are given at a higher dose in order to kill the cancer cells.

“The chemotherapy tends to be very intensive,” said Cooper. “Some of the most effective medicines work really well against leukemia, but the side effects, including damage to the heart, can be severe.”

CPX-351 delivers chemotherapy in a different way than standard chemotherapy. The medicines are contained in a liposomal formulation which is thought to be safer for the heart. The liposome is used as a vehicle to transport the drugs into the body and into leukemia cells in the bone marrow. We hope that by being housed inside the liposome, that less of the chemotherapy will be deposited into the heart.

In phase 3 trials for adults with high-risk, secondary AML, there was a statistically significant improvement in overall survival compared to patients who received a regimen using chemotherapy drugs delivered in the standard way. The use of CPX-351 reduced the risk of death by 31% compared to the use of the chemotherapy drugs cytarabine and daunorubicin.

“This trial not only offers hope for more children to be cured, but for more children to live longer, leading more productive lives without late term cardiac damage,” said Cooper. “I am thrilled to bring this therapy to children through the trial because I want kids to have access as soon as possible to these potentially lifesaving drugs.”

Although results from the trial will not be completed for a couple of years, Cooper is optimistic CPX-351 will improve outcomes for children with relapsed AML and may one day become a frontline treatment.

Stem Cell-Based Test Predicts Leukemia Patients’ Response to Therapy to Help Tailor Treatment

Newswise — (TORONTO, Canada – Dec. 7, 2016) – Leukemia researchers at Princess Margaret Cancer Centre have developed a 17-gene signature derived from leukemia stem cells that can predict at diagnosis if patients with acute myeloid leukemia (AML) will respond to standard treatment.

The findings, published online today in Nature, could potentially transform patient care in AML by giving clinicians a risk scoring tool that within a day or two of diagnosis can predict individual response and help guide treatment decisions, says co-principal investigator Dr. Jean Wang, Affiliate Scientist at the Princess Margaret, University Health Network (UHN). Dr. Wang is also an Assistant Professor, Faculty of Medicine, University of Toronto and a Hematologist at Toronto General Hospital, UHN. She talks about the research at https://youtu.be/ilSiyUP9HE0.

The new biomarker is named the LSC17 score as it comes from the leukemia stem cells that drive disease and relapse. These dormant stem cells have properties that allow them to resist standard chemotherapy, which is designed to defeat rapidly dividing cancer cells. The persistence of these stem cells is the reason the cancer comes back in patients despite being in remission following treatment. AML is one of the most deadly types of leukemia and the most common type of acute leukemia in adults; it increases in frequency as we age. In Canada, there are more than 1,200 new cases each year. The five-year survival ranges between 20% – 30% and is lower in older people.

The study authors write that using the LSC17 score to single out high-risk patients predicted to have resistant disease “provides clinicians with a rapid and powerful tool to identify AML patients who are less likely to be cured by standard therapy and who could be enrolled in trials evaluating novel upfront or post-remission strategies.”

The researchers identified the LSC17 score by sampling the leukemia stem cell properties of blood or bone marrow samples from 78 AML patients from the cancer centre combined with molecular profiling technology that measures gene expression. Stanley W. K. Ng, a senior PhD candidate in the lab of Dr. Peter Zandstra at the Institute for Biomaterials and Biomedical Engineering, University of Toronto and co-lead author of the paper, used rigorous statistical approaches to develop and test the new “stemness score”, using AML patient data provided by the Princess Margaret leukemia clinic and collaborators in the United States and Europe.

“We identified the minimal set of genes that were most critical for predicting survival in these other groups of AML patients, regardless of where they were treated. With this core 17-gene score, we have shown we can rapidly measure risk in newly diagnosed AML patients,” says Dr. Wang.

In the study, analysis of patient samples demonstrated that high LSC17 scores meant poor outcomes with current standard treatment, even for patients who had undergone allogeneic stem cell transplantation. A low score indicated a patient would respond well to standard treatment and have a long-term remission.

The test to measure the LSC17 score has been adapted to a technology platform called NanoString. As the research team and international collaborators continue to validate the stemness risk score, plans are under way to test the score in a clinical trial at the Princess Margaret, which now has the NanoString system in its molecular diagnostic laboratory.

Dr. Wang explains that the fast turnaround time to measure the LSC17 score on the NanoString system will be key to moving the test into the clinic.

“The LSC17 score is the most powerful predictive and prognostic biomarker currently available for AML, and is the first stem cell-based biomarker developed in this way for any human cancer,” says Dr. Wang. “Clinicians will now have a tool that they can use upfront to tailor treatment to risk in AML.”

The research was funded by the Ontario Institute for Cancer Research, the Cancer Stem Cell Consortium via Genome Canada and the Ontario Genomics Institute; the Canadian Institutes of Health Research, Canadian Cancer Society, Terry Fox Foundation; the Canada Research Chair in Stem Cell Biology (Dr. John Dick), the Leukemia & Lymphoma Society of Canada, the Stem Cell Network, the Orsino Chair in Leukemia Research (Dr. Mark Minden), The Princess Margaret Cancer Foundation, and the Ontario Ministry of Health and Long-Term Care. This work was made possible by the generous contributions of blood and bone marrow samples by AML patients to research.

Leukemia Drug Combo Is Encouraging in Early Phase I Clinical Trial

In a small study, 67 percent of leukemia patients treated with combination of thioguanine and decitabine responded to treatment

Researchers from Columbia University Medical Center and NewYork-Presbyterian reported that 8 out of 12 patients with relapsed and/or chemotherapy refractory acute myeloid leukemia (AML) or other blood cancers responded to a regimen including the chemotherapy drugs thioguanine and decitabine. Results from this small phase I study were reported at the American Society of Hematology’s annual conference.

“Outcomes are typically poor for older patients with advanced blood cancers, and new therapies are desperately needed to help patients with these cancers achieve remission,” said Mark Frattini, MD, PhD, associate professor of medicine at Columbia University Medical Center (CUMC) and blood cancer specialist at NewYork-Presbyterian. “While our study was small, the response we saw in this phase I, dose-escalating trial was encouraging.”

Previously, Frattini and colleagues had used a proprietary chemosensitivity screening assay to demonstrate that combining thioguanine and decitabine—chemotherapy drugs that are commonly used as single agents to treat patients with AML—restored therapeutic efficacy in leukemia cells from patients with relapsed and/or refractory disease.

In this study, the researchers tested the efficacy of the combination therapy in 12 older patients (median age of 67 years) with relapsed or chemotherapy refractory AML or chronic myelomonocytic leukemia, including 6 patients whose disease progressed after being treated previously with decitabine as a single agent. Of these, 11 patients completed the first treatment cycle, and 6 completed a second cycle, with a median of 3 rounds of treatment. Eight of the 11 evaluable patients responded to the combination therapy, including 6 who achieved a complete remission (5 in complete remission with incomplete count recovery). In addition, all of the patients who had progressed after prior treatment with decitabine alone responded to the combination therapy, demonstrating that the combination could overcome disease resistance to decitabine. Chemosensitivity assay results, obtained before treatment, accurately predicted each patient’s response to the combination therapy.

After treatment with the combination therapy, 4 of the responders went on to have a stem cell transplant.

“The goal of chemotherapy for patients with relapsed and/or refractory AML and other blood cancers is to achieve a remission that enables them to undergo a potentially curative stem cell transplant,” said Dr. Frattini. “With our phase I results, we have shown that this combination therapy can get some patients—including those who failed to respond to or progressed after previous chemotherapy treatment with a single agent such as decitabine—to that point. The next challenge for hematologic oncologists is to reduce morbidity and mortality associated with stem cell transplantation.”

After the study, 2 of the patients who had a stem cell transplant died from transplant-related toxicity, and another relapsed. One patient has remained in remission for more than 2 years.

Experimental CAR-T Treatment Halted as Two More Patients Die During Clinical Trials

Juno Therapeutics said Wednesday it has suspended a Phase II clinical trial of a cancer drug after two patients suffered cerebral edema earlier this week, leaving one dead and the other not expected to recover. The company’s ‘Rocket’ trial for B cell acute lymphoblastic leukemia is testing a drug it calls JCAR015.

These drugs work by extracting T cells from patients and then equipping them with chimeric antigen receptors, which then zero in on cancer cells. This first generation of CAR-Ts, which is likely to be eclipsed by early-stage efforts, has been known to trigger harsh side effects.

The cause of death in these patients was cerebral edema, or swelling in the brain. Cerebral edema was the same condition that killed three patients earlier this year and forced the company to stop the trial in this summer. Juno, at that time, had blamed the deadly reaction on one of the chemotherapy drugs that it was using to “precondition,” or prepare the patients for JCAR015. The FDA allowed Juno to restart the trial in short order, however, without the chemo drug, called fludarabine.

Juno said it has notified the Food and Drug Administration of the voluntary hold and is working with the agency and the Data and Safety Monitoring Board to determine next steps. Juno’s trials and plans for its other product candidates are not affected, the company said in a prepared statement.

 

Long-Sought Genetic Model Of Common Infant Leukemia Described

After nearly two decades of unsuccessful attempts, researchers from the University of Chicago Medicine and the Cincinnati Children’s Hospital Medical Center have created the first mouse model for the most common form of infant leukemia. Their discovery, published in the Nov. 14, 2016, issue of Cancer Cell, could hasten development and testing of new drug therapies.

Pro-B acute lymphoblastic leukemia (ALL) with the (4;11) translocation is responsible for about 70 percent of infant and 10 percent of both childhood and adult acute lymphoblastic leukemias. The new mouse model replicates the human genetic flaw that causes this disease, making it much easier to study.

This subtype of leukemia results from a genetic fusion t(4;11), known as a translocation. This combines parts of two separate genes. One of those genes, MLL (short for mixed-lineage leukemia), comes from chromosome 11. The other fragment, AF4 (short for ALL fused gene) from chromosome 4. The hybrid MLL-AF4 gene results in leukemia.

Children and adults with this disease produce vast numbers of dysfunctional blood cells, which eventually crowd out functional cells. MLL-AF4 leukemia has a dismal prognosis, among the worst of any subset of acute leukemia.

“For 20 years, scientists have repeatedly tried and consistently failed to make a model of MLL-AF4 Pro-B acute lymphoblastic leukemia,” said Michael Thirman, MD, Associate Professor of Medicine at the University of Chicago. “Even though we understood the basic genetic flaw, no one had been able create a mouse model that mimicked the human disease, which is crucial for evaluating potential therapies.”

That frustrated many researchers, who shifted their focus to test alternative hypotheses on the causes of this leukemia or refocused their laboratories to study different aspects of this disease.

Thirman’s team, including longtime colleague Roger Luo, PhD, began working on this problem “years ago,” he said, and stayed with it. They quickly identified two hurdles.

The first was a problem with the retrovirus that scientists used to insert the leukemia-causing gene into mouse cells. That gene, acquired from leukemia patients, consisted of a human gene fragment from MLL linked to the human fragment from AF4.

“We soon discovered that the virus wasn’t working,” Thirman explained. “We knew that certain parts of human DNA can decrease viral titers. So we switched from the human version of AF4 to the mouse version, Af4, which is slightly different. This increased viral titers 30 fold.”

That worked, but it led to hurdle two. The mice injected with virus transporting MLL-Af4 developed leukemia, but it was the wrong kind. They developed acute myeloid instead of acute lymphoblastic leukemia. “Despite the use of lymphoid conditions,” the study authors wrote, “no lymphoid leukemia was observed.”

Next, they collaborated with James Mulloy, PhD, at Cincinnati Children’s Hospital Medical Center, whose graduate student Shan Lin inserted the fused MLL-Af4 gene into human CD34 cells, derived from cord or peripheral blood from volunteer donors. They transferred those cells to mice with immune systems that permit the growth of human cells. This time, the mice developed Pro-B ALL, identical to the leukemia found in humans.

“The model worked perfectly,” Thirman said. Within 22 weeks, all of the mice developed exactly the same type of leukemia as observed in patients.

Expression of MLL-Af4 in human cells “recapitulates the pro-B ALL observed in patient with t(4:11) as shown by immunophenotype, chromatin targeting of the fusion, nuclear complex formation, and gene expression signatures,” the authors wrote. “It mimics the disease found in humans both phenotypically and molecularly.”

“The differences in the type of leukemia that developed using mouse versus human cells were striking,” said Mulloy. “Researchers need to consider these differences carefully when choosing which model to use to mimic human disease. The available evidence now indicates that the approaches are not equivalent.”

They conclude that “our MLL-Af4 model will be a valuable tool to study this most prevalent MLL-fusion leukemia with such a poor prognosis.”

However, there is more work to be done. “MLL fusion disease is not a single genetic entity,” the authors note. “Each has its own genetic and biological features associated with particular fusion partners.” This highlights the need for “more models specific to each fusion. Our MLL-Af4 model will be a valuable tool.”

Antibody Breaks Leukemia’s Hold, Providing New Therapeutic Approach

Acute myeloid leukemia (AML) is an aggressive cancer known for drug resistance and relapse. In an effort to uncover new treatment strategies, researchers at University of California San Diego School of Medicine and Moores Cancer Center discovered that a cell surface molecule known as CD98 promotes AML. The study, published October 27 by Cancer Cell, also shows that inhibiting CD98 with the therapeutic antibody IGN523 blocks AML growth in patient-derived cells and mouse models.

“To improve therapeutic strategies for this disease, we need to look not just at the cancer cells themselves, but also at their interactions with surrounding cells, tissues, molecules and blood vessels in the body,” said co-senior author Tannishtha Reya, PhD, professor of pharmacology at UC San Diego School of Medicine and Moores Cancer Center. “In this study, we identified CD98 as a critical molecule driving AML growth. We showed that blocking CD98 can effectively reduce leukemia burden and improve survival by preventing cancer cells from receiving support from the surrounding environment.”

Reya led the study together with Mark Ginsberg, MD, professor of medicine at UC San Diego School of Medicine and Moores Cancer Center. Co-author Edward van der Horst, PhD, senior director at Igenica Biotherapeutics Inc., provided the anti-CD98 antibody IGN523.

AML is a type of cancer in which the bone marrow makes abnormal white blood cells, red blood cells or platelets. Reya’s team and others have previously shown that leukemia cells interact with their surroundings in the body via molecules on their cell surfaces, and that these interactions can help the cancer cells divide, replicate and metastasize.

CD98 is a molecule found on the surface of cells, where it controls how cells stick to one another. CD98 is known to play a role in the proliferation and activation of certain immune cells. CD98 levels are also known to be elevated in some solid tumors, and linked to poor prognosis.

To determine CD98’s role in AML, in this latest study Reya’s team engineered mouse models that lack the molecule. They found that the loss of CD98 blocked AML growth and improved survival. CD98 loss largely spared normal blood cells, which the researchers said indicates a potential therapeutic window. Further experiments revealed that leukemia cells lacking CD98 had fewer stable interactions with the lining of blood vessels — interactions that were needed to fuel AML growth.

Next, the researchers wanted to see what would happen if they blocked CD98 in AML with a deliverable inhibitor. In 2015, Igenica Biotherapeutics Inc. tested IGN523, a humanized antibody that specifically binds and inhibits CD98, in a phase 1 clinical trial at Moores Cancer Center and elsewhere. The trial’s goal was to determine a safe dose for IGN523 administration in AML patients. In this study, Reya and team tested IGN523 in their own AML models.

The researchers found that IGN523 blocks CD98’s AML-promoting activity in both mouse models of AML and human cells in the laboratory. They also transplanted human patient-derived AML cells into mice and treated the recipients soon after with either IGN523, the anti-CD98 antibody, or with a control antibody. Anti-CD98-treatment effectively eliminated AML cells. In contrast, AML in control mice expanded more than 100-fold.

“This study suggests that human AML can’t get established without CD98, and that blocking the molecule with anti-CD98 antibodies could be beneficial for the treatment of AML in both adults and children,” Reya said.

Moving forward, Reya and team are working to further define whether CD98 could be targeted to treat pediatric AML.

“Many of the models we used in this work were based on mutations found in childhood AML,” she said. “While many childhood cancers have become very treatable, childhood AML continues to have a high rate of relapse and death. We plan to work with pediatric oncologists to test if anti-CD98 agents can be effective against pediatric AML, and whether it can improve responses to current treatments. I think this is particularly important to pursue since the anti-CD98 antibody has already been through phase I trials, and could be more easily positioned to test in drug-resistant pediatric AML.”

The American Cancer Society estimates that there will be about 19,950 new cases of AML and about 10,430 deaths from the disease in the United States in 2016, mostly adults. Approximately 500 children are diagnosed with AML in the U.S. each year, and it’s the most common second cancer among children treated for other cancers, according to St. Jude Children’s Research Hospital.

Brain Cancer And Leukemia: New Molecular Mechanisms Decoded

Brain cancer and leukemia are two potentially fatal diseases that affect thousands of Canadians each year. But a joint study conducted by researchers Frederick Antoine Mallette, of the Maisonneuve-Rosemont Hospital Research Centre and the University of Montreal, and Marc-Étienne Huot, of Laval University, and published in the prestigious scientific journal Nature Communications has uncovered new molecular causes of brain cancer and leukemia.

We already knew the existence of a mutation phenomenon involving certain metabolic enzymes called isocitrate dehydrogenases 1 and 2 (IDH1/2) in various forms of brain cancer, including gliomas and glioblastomas, and in acute myeloid leukemia. Although the mutated forms of IDH1/2 appear to contribute to cancer formation, until now we had only limited understanding of the ways in which these metabolic defects caused cancer. Research conducted by Mélissa Carbonneau, a master’s student in Professor Mallette’s laboratory, has helped to better understand the effect of IDH1/2 mutations in cancer by demonstrating their role in activating the pathways involved in cell proliferation and survival.

“With the identification of the molecular modes of action that contribute to cancer in patients carrying IDH1/2 mutations, it is now possible to consider personalized treatment to potentially improve therapeutic response,” said Dr. Mallette.
Some statistics

It is estimated that in 2015, 3,000 Canadians were diagnosed with brain and spinal cord cancer, and 6,200 Canadians were diagnosed with leukemia.

Blood Cancer Treatment May Age Immune Cells As Much As 30 Years

Certain cancer treatments are known to take a toll on patients, causing side effects like fatigue, nausea and hair loss. Now, scientists are investigating whether some treatments can cause another long-term side effect: premature aging of important disease-fighting cells.

University of North Carolina Lineberger Comprehensive Cancer Center researchers, by tracking a molecular marker that has been shown to increase in white blood cells as people age, have uncovered clues that suggest that stem cell transplant is linked to a marked increase in the “molecular age” of these immune cells in a group of patients with blood cancer.

The researchers report in the journal EBioMedicine that patients treated with an autologous stem cell transplant – a procedure that uses a reserve of a patient’s own stem cells to regenerate healthy, non-cancerous blood cells – had elevated levels of expression of messenger RNA (mRNA), a type of genetic code used to make proteins, for this age-related marker. Strikingly, they found expression levels increased to a degree comparable to an additional 30 years of chronological age.

Despite the risk for significant short- and long-term side effects, the researchers say stem cell transplant is an extremely important treatment option. They believe their findings could lay the foundation for future studies into using this age marker to enable physicians to better quantify a patient’s potential risk and benefit associated with a stem cell transplant.

“We know that transplant is life-prolonging, and in many cases, it’s life-saving, for many patients with blood cancers and other disorders,” said the study’s lead author William Wood, MD, a UNC Lineberger member and an associate professor in the UNC School of Medicine Division of Hematology and Oncology. “At the same time, we’re increasingly recognizing that survivors of transplant are at risk for long-term health problems, and so there is interest in determining what markers may exist to help predict risk for long-term health problems, or even in helping choose which patients are best candidates for transplantation.”

Researchers are interested in objective measures of molecular or functional age as a person’s age in years is not always a good indicator of his or her health or fitness to receive a treatment. UNC Lineberger researchers examined mRNA levels for a protein called p16. MRNA expression of the gene coding for the p16 protein has been found to exponentially increase with chronological age.

“It’s a well-known concept in geriatric oncology that different people age biologically at different rates and that their overall health status may or may not correspond with chronological age,” Wood said. “ On the one hand, we would not want to use chronological age itself to exclude patients from transplant since there are now patients up to the age of 80 who would benefit from transplant if they are otherwise appropriate candidates. A measure of biological age could help us to identify appropriate older candidates who might have previously been excluded from transplant. On the other hand, there are other, potentially younger patients who may be less physiologically fit because of prior treatment or comorbid illness, for whom transplant carries increased risks.”

UNC Lineberger researchers studied the impact of two different transplant types: autologous stem cell transplant, which uses a patient’s own stem cells, and allogeneic stem-cell transplant, which uses a stem cells from a donor, on 63 patients treated at UNC Hospitals for myeloma, lymphoma or leukemia.

The researchers reported higher expression of mRNA coding for p16 in the T-cells of both patients who received allogeneic and autologous transplant, but patients receiving autologous transplant had a larger increase — three times their pre-transplant levels.

They also noted that autologous stem cell transplant, as measured by p16 mRNA expression, had the strongest impact on molecular aging of T-cells — even greater than cytotoxic chemotherapy. A previous study had found that cytotoxic chemotherapy in breast cancer led to an approximately two-fold increase in p16 mRNA expression, equivalent to about 10 years of chronological aging.

To try to explain why autologous stem cell transplant might age T-cells faster, they speculated that the forced regeneration of bone marrow that accompanies re-engraftment may contribute to stem cell aging. Chemotherapy prior to transplant may also contribute to increased p16 mRNA expression – so recipients of autologous transplant are in effect aged twice.

While the researchers did not have data showing a clear connection between changes in p16 mRNA expression levels and the actual function of the T-cells, they did argue that expression of this marker is “arguably one of the best in vivo marker of cellular senescence and is directly associated with age-related deterioration.”

“Many oncologists would not be surprised by the finding that stem cell transplant accelerates aspects of aging,” said the study’s senior author Norman Sharpless, MD, director of UNC Lineberger and the Wellcome Distinguished Professor in Cancer Research. “We know that years after a curative transplant, stem cell transplant survivors are at increased risk for blood problems that can occur with aging, such as reduced immunity, increased risk for bone marrow failure, and increased risk of blood cancers. What is important about this work, however, is that it allows us to quantify the effect of stem cell transplant on molecular age.”

RESEARCHERS DEVELOP NEW STRATEGY TO LIMIT SIDE EFFECTS OF STEM CELL TRANSPLANTS

Scientists in Germany have developed a new approach that may prevent leukemia and lymphoma patients from developing graft-versus-host disease (GvHD) after therapeutic bone marrow transplants. The researchers describe the successful application of their strategy in mice in “Exogenous TNFR2 activation protects from acute GvHD via host T reg cell expansion,” which will be published online August 15 ahead of issue in The Journal of Experimental Medicine.

Bone marrow transplants can cure types of leukemia and lymphoma because hematopoietic stem cells derived from the donor’s bone marrow can develop into immune cells capable of killing the patient’s tumor cells. But the donor-derived immune cells may also attack the transplant recipient’s healthy tissues, producing the diverse and sometimes severe symptoms of GvHD. One approach to avoiding GvHD is to co-transplant large numbers of regulatory T cells (T reg cells), immune cells that can suppress the donor cells’ effects on healthy tissue while maintaining their ability to kill tumor cells. This approach is challenging, however, because the T reg cells must first be isolated from the donor’s peripheral blood or bone marrow and then cultivated in the laboratory to produce sufficient numbers for transplantation.

A team of researchers led by Andreas Beilhack and Harald Wajant of the University Hospital Wϋrzburg devised an alternative way to prevent GvHD in mice, developing a protein called STAR2 that can stimulate the formation of the transplant recipient’s own T reg cells in vivo. Pretreating mice with STAR2 protected them from developing GvHD after immune cell transplantation. The donor-derived cells retained their ability to kill the recipient’s lymphoma cells, however.

STAR2 works by specifically binding to a cell surface protein called TNFR2, activating a signaling pathway that increases the number of T reg cells. Beilhack and colleagues found that a slightly modified version of STAR2 has a similar effect on human T reg cells, suggesting that the approach could also prevent GvHD in leukemia and lymphoma patients after bone marrow or hematopoietic stem cell transplants. “Furthermore, this strategy may be beneficial for other pathological settings in which elevated numbers of regulatory T cells are desirable, such as autoimmune diseases and solid organ transplantation,” Beilhack says.

Researchers inhibit tumor growth in new subtype of lung cancer

Lung cancer is the most common cause of cancer deaths, accounting for about a third of all tumor-related deaths. Adenocarcinomas, a non-small cell lung cancer (NSCLC), account for about 40 percent of cancer diagnoses, but few treatments are available for the disease.

A team of investigators led by Elena Levantini, PhD, a research associate in Hematology-Oncology at Beth Israel Deaconess Medical Center (BIDMC), instructor of medicine at Harvard Medical School and a member of the Harvard Stem Cell Institute, have identified a subtype of human adenocarcinoma. The research could help determine which individuals are at greatest risk of developing lung tumors that may be amenable to a new therapy to inhibit their progression. The results – done in collaboration with the Cancer Science Institute at the National University of Singapore (CSI NUS) – were published today in the journal Science Translational Medicine.

“Advances in lung cancer therapy require a greater understanding of the molecular origins of this deadly disease,” said last corresponding author Levantini, who is also a researcher at the Institute of Biomedical Technologies at the Italian National Research Council (ITB-CNR). “Understanding the differences among lung cancers also could lead to innovations in treatment strategies and allow us to overcome drug-resistance, relapse and disease progression.”

Levantini and colleagues previously showed that NSCLC tumor cells frequently express too little or none of a transcription factor called C/EBPα, a protein that regulates gene expression and cell proliferation in lung tissues. It’s also known to play a role in a form of leukemia, as well as liver cancer, squamous cell skin carcinomas, squamous cell cancers of the head and neck and other cancers. In their previous work, the scientists suspected that C/EBPα may act as a tumor suppressant in normal cells, but the mechanism by which its absence promoted lung cancer tumors remained unclear.

In a series of in vitro experiments, the researchers demonstrated that C/EBPα indeed works as a tumor suppressant by restraining the expression of another molecule known to play a role in triggering and maintaining tumor growth. This molecule, called BMI1, is an oncogenic protein that has been implicated in colon cancer, a form of leukemia and breast and gastric cancers.

To determine the relationship between the suspected tumor suppressor (C/EBPα) and the oncogenic protein (BMI1), the researchers first altered a line of human adenocarcinoma cells to overexpress C/EBPα. That led to a marked reduction in the expression of BMI1. When the team analyzed tissues from 261 patients with NSCLC, they found an inverse correlation between the two molecules; that is, more than 80 percent of patient tissues with low levels of the tumor suppressing C/EBPα were positive for BMI1 expression. Likewise, an analysis tissue samples from patients with lung adenocarcinoma with no or low C/EBPα expression revealed that those with lower levels of BMI1 were more likely to survive, a pattern that has prognostic value, the researchers wrote.

“Our findings suggest that the lung cancer subtype defined by the loss of C/EBPα expression might specifically benefit from therapies that inhibit BMI1,” the scientists wrote. “Thus, identifying factors that modulate its expression has generated major clinical interest.”

The research team was also able to validate its findings in mice. In one set of experiments with mice engineered to express no C/EBPα, the scientists found an inverse relationship between the transcription factor and BMI1 that was nearly identical to its data from human adenocarcinoma. By manipulating BMI1 expression in vivo, the researchers were also able to confirm that decreasing the expression of the oncogenic protein was enough to fully inhibit tumor formation and even significantly arrest tumor growth.

“BMI1 plays a substantial role in many solid tumors, including one of the most aggressive models of lung cancer, and its expression is linked with tumor growth, invasion, metastasis, prognosis and recurrence,” Levantini said. “Our findings could help us design better therapies for the subset of adenocarcinoma patients with low C/EBPα and high BMI1 expression pattern.”

Hybrid Treatment Hunts Down and Kills Leukemia Cells

Researchers at UC Davis and Ionis Pharmaceuticals have developed a hybrid treatment that harnesses a monoclonal antibody to deliver antisense DNA to acute lymphoblastic leukemia (ALL) cells and that may lead to less toxic treatments for the disease.

The study, published in the journal Molecular Medicine, demonstrated that once delivered, the therapeutic DNA reduced levels of MXD3, a protein that helps cancer cells survive. This novel conjugate therapy showed great promise in animal models, destroying ALL cells while limiting other damage.

“We’ve shown, for the first time, that anti-CD22 antibody-antisense conjugates are a potential therapeutic agent for ALL,” said Noriko Satake, associate professor in the Department of Pediatrics at UC Davis. “This could be a new type of treatment that kills leukemia cells with few side effects.”

ALL is the most common type of childhood cancer. It is a disease in which the bone marrow makes too many immature lymphocytes, a type of white blood cell. While most children survive ALL, many patients suffer late or long-term side effects from treatment, which may include heart problems, growth and development delays, secondary cancers and infertility.

Antisense oligonucleotides are single strands of DNA that can bind to messenger RNA, preventing it from making a protein. While antisense technology has long shown therapeutic potential, getting the genetic material inside target cells has been a problem.

In the study, researchers attached antisense DNA that inhibits the MXD3 protein to an antibody that binds to CD22, a protein receptor expressed almost exclusively in ALL cells and normal B cells.

Once the antibody binds to CD22, the conjugate is drawn inside the leukemia cell, allowing the antisense molecule to prevent MXD3 production. Without this anti-apoptotic protein, ALL cells are more prone to cell death.

The hybrid treatment was effective against ALL cell lines in vitro and primary (patient-derived) ALL cells in a xenograft mouse model. Animals that received the hybrid therapy survived significantly longer than those in the control group.

Designed to be selective, the treatment only targets cells that express CD22. While it does attack healthy B cells, the therapy is expected to leave blood stem cells and other tissues unscathed.

“You really don’t want to destroy hematopoietic stem cells because then you have to do a stem cell transplant, which is an extremely intensive therapy,” noted Satake. “Our novel conjugate is designed so that it does not harm hair, eyes, heart, kidneys or other types of cells.”

While the study shows the conjugate knocked down MXD3, researchers still have to figure out how this was accomplished. In addition, they will investigate combining this treatment with other therapies. Because it hastens cell death, the conjugate could make traditional chemotherapy drugs more effective. In addition, the approach might work against other cancers.

“You can see this as proof of principle,” Satake said. “You could switch the target and substitute the antibody, which could be used to treat other cancers or even other diseases.”

Body’s Own Gene Editing System Generates Leukemia Stem Cells

Cancer stem cells are like zombies — even after a tumor is destroyed, they can keep coming back. These cells have an unlimited capacity to regenerate themselves, making more cancer stem cells and more tumors. Researchers at University of California San Diego School of Medicine have now unraveled how pre-leukemic white blood cell precursors become leukemia stem cells. The study, published June 9 in Cell Stem Cell, used human cells to define the RNA editing enzyme ADAR1’s role in leukemia, and find a way to stop it.

While DNA is like the architect’s blueprint for a cell, RNA is the like the engineer’s interpretation of the blueprint. That RNA version is frequently flawed in cancer. While many studies have uncovered pivotal DNA mutations in cancer, few have addressed the roles of RNA and mechanisms that regulate RNA.

“In this study, we showed that cancer stem cells co-opt a RNA editing system to clone themselves. What’s more, we found a method to dial it down,” said senior author Catriona Jamieson, MD, PhD, associate professor of medicine and chief of the Division of Regenerative Medicine at UC San Diego School of Medicine.

The enzyme at the center of this study, ADAR1, can edit the sequence of microRNAs, small pieces of genetic material. By swapping out just one microRNA building block for another, ADAR1 alters the carefully orchestrated system cells use to control which genes are turned on or off at which times.

ADAR1 is known to promote cancer progression and resistance to therapy. In this study, Jamieson’s team used human blast crisis chronic myeloid leukemia cells in the lab, and mice transplanted with these cells, to determine ADAR1’s role in governing leukemia stem cells.

The researchers uncovered a series of molecular events. First, white blood cells with a leukemia-promoting gene mutation become more sensitive to signs of inflammation. That inflammatory response activates ADAR1. Then, hyper-ADAR1 editing slows down the microRNAs known as let-7. Ultimately, this activity increases cellular regeneration, or self-renewal, turning white blood cell precursors into leukemia stem cells. Leukemia stem cells promote an aggressive, therapy-resistant form of the disease called blast crisis.

“This is the first mechanistic link between pro-cancer inflammatory signals and RNA editing-driven reprogramming of precursor cells into leukemia stem cells,” said Jamieson, who is also deputy director of the Sanford Stem Cell Clinical Center at UC San Diego Health, director of the CIRM Alpha Stem Cell Clinic at UC San Diego School of Medicine and director of stem cell research at UC San Diego Moores Cancer Center.

After learning how the ADAR1 system works, Jamieson’s team looked for a way to stop it. By inhibiting sensitivity to inflammation or inhibiting ADAR1 with a small molecule tool compound, the researchers were able to counter ADAR1’s effect on leukemia stem cell self-renewal and restore let-7. Self-renewal of blast crisis chronic myeloid leukemia cells was reduced by approximately 40 percent when treated with the small molecule, called 8-Aza, as compared to untreated cells.

“Based on this research, we believe that detecting ADAR1 activity will be important for predicting cancer progression. In addition, inhibiting this enzyme represents a unique therapeutic vulnerability in cancer stem cells with active inflammatory signaling that may respond to pharmacologic inhibitors of inflammation sensitivity or selective ADAR1 inhibitors that are currently being developed,” Jamieson said.